Argument S to typeof is not an expression

[Jacob Carlborg]

On 2013-05-07 08:41, Meta wrote:
> template Test(alias N)
> if (isIntegral!(typeof(N)))
> {
>      struct S
>      {
>          typeof(N) n = N;
>
>          auto opAdd(T)(T rhs)
>          {
>              //Error: argument S to typeof is not an expression
>              pragma(msg, typeof(T));
>              //Error: variable rhs cannot be read at compile time
>              return Test!(n + rhs.n);
>          }
>      }
>      auto st = S(N);
>      alias Test = st;
> }
>
> void main()
> {
>      auto a = Test!2;
>      auto b = Test!3;
>      writeln(typeof(a).stringof ~ " a = ", a, ", ",
>              typeof(b).stringof ~ " b = ", b, ", ",
>              typeof(a + b).stringof ~ " a + b = ");
> }
>
> I don't really understand why either of these error messages are
> occurring. The first is just incomprehensible, and the second seems like
> it should work. In this case, rhs is fully accessible at compile time in
> the expression (a + b), so why does the compiler complain?

As a workaround for "typeof" you can use this:

https://github.com/jacob-carlborg/orange/blob/master/orange/util/Traits.d#L213

-- 
/Jacob Carlborg